Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein I is a neuron-specific, synaptic phosphoprotein highly localized on the surface of synaptic vesicles. We have recently isolated anti-Protein I IgG by affinity chromatography and shown that these antibodies inhibit specifically the phosphorylation of Protein I (Naito, S., and Ueda, T. (1981) J. Biol. Chem. 256, 10657-10663). In an effort to characterize Protein I-associated synaptic vesicles with respect to the types of neurotransmitters, we have now developed a procedure, using the affinity-purified anti-Protein I IgG, which allows immunoprecipitation of those synaptic vesicles which contain Protein I. The isolated vesicles are largely free of contamination from other intracellular organelles and plasma membranes. We present evidence that these vesicles isolated from bovine cortex are able to accumulate L-glutamate specifically in an ATP-dependent, temperature-dependent but Na-independent manner. Thus, the structurally similar aminoacid neurotransmitters aspartate and gamma-aminobutyric acid, as well as other neurotransmitters such as dopamine, norepinephrine, serotonin, acetylcholine, and glycine, failed to show a significant ATP-dependent uptake into these vesicles. Moreover, the ATP-dependent glutamate uptake was not inhibited effectively by glutamine, aspartate, or gamma-aminobutyric acid. The ATP-dependent glutamate uptake requires ATP hydrolysis; thus there was little accumulation of glutamate in the absence of ATP or Mg2+, or when ATP was replaced by an unhydrolyzable beta, gamma-methylene ATP analog. The glutamate uptake appears to be driven at least in part by a membrane potential generated by Mg2+-ATPase, similar to that of the catecholamine and serotonin uptakes into storage granules. These observations suggest that Protein I may be involved in some aspect of the function of glutamate-containing synaptic vesicles in the brain.
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PMID:Adenosine triphosphate-dependent uptake of glutamate into protein I-associated synaptic vesicles. 613 88

A rat cerebral cortical slice preparation was used to study the response of transmitter release to the application of the food dye, Erythrosin B, a tetraiodinated derivative of fluorescein. Erythrosin B (100 microM) stimulated net release of previously taken up [3H]norepinephrine and [3H]gamma-aminobutyric acid (GABA). The Erythrosin-induced release of GABA (the only transmitter studied) occurred in the absence of added Ca2+, and in the presence of tetrodotoxin (TTX). Ultrastructural analysis of the vesicle content of frog neuromuscular junctions treated with Erythrosin B revealed a diminution in the number of synaptic vesicles present in the nerve terminal. By using fluorescein and some halogen-substituted derivatives including Erythrosin B, it was found that incubation with the unhalogenated compound caused no net release, whereas incubation with the iodine-, chlorine- or bromine-substituted compound did cause release. It was also found that somewhat greater release induced by Erythrosin B (at 100 microM) occurred in the light than in the dark. That Erythrosin B inhibits the Na+,K+,Mg2+-ATPase was confirmed in this preparation; it did so in both light and dark. The discrepancy between release and Na+,K+,Mg2+-ATPase blockade in the dark suggests that release either occurs by some other mechanism than by Na+,K+,Mg2+-ATPase blockade, or that an additional light-dependent process contributes to the release. We conclude that Erythrosin B can presumably induce net release of transmitters generally, that release does not occur via the TTX-sensitive Na+ channel, that release via vesicles does occur, and that light somewhat enhances the release.
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PMID:Characterization of transmitter release as a response of vertebrate neural tissue to erythrosin B. 614 88

Preincubation of plasma membranes from bream brain with 10-8-10-4 M gamma-aminobutyric acid (GABA) or muscimol increased the anion-sensitive Mg2+-ATPase activity. The activating effect of neurotransmitters on the Mg2+-ATPase is enhanced with increasing preincubation time of the membranes with the ligands, decreases with increasing Mg2+-ATP concentration in the incubation medium, and is inhibited in the presence of the GABAa-receptor antagonist, bicuculline (90 microgr;M). The anions Cl-, Br-, and I- stimulate the basal Mg2+-ATPase activity, and an effect of 10-4 M GABA in the presence of anions was not found. It is supposed that GABAergic chemicals modify the anion-sensitive Mg2+-ATPase in a receptor-dependent way.
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PMID:Effect of GABAergic compounds on the anion-sensitive Mg2+-ATPase from bream (Abramis brama L.) brain. 1085 Oct 43